﻿using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
public class ShareMem
{
    [DllImport("user32.dll", CharSet = CharSet.Auto)]
    public static extern IntPtr SendMessage(IntPtr hWnd, int Msg, int wParam, IntPtr lParam);
    [DllImport("Kernel32.dll", CharSet = CharSet.Auto)]
    public static extern IntPtr CreateFileMapping(int hFile, IntPtr lpAttributes, uint flProtect, uint dwMaxSizeHi, uint dwMaxSizeLow, string lpName);
    [DllImport("Kernel32.dll", CharSet = CharSet.Auto)]
    public static extern IntPtr OpenFileMapping(int dwDesiredAccess, [MarshalAs(UnmanagedType.Bool)]bool bInheritHandle, string lpName);
    [DllImport("Kernel32.dll", CharSet = CharSet.Auto)]
    public static extern IntPtr MapViewOfFile(IntPtr hFileMapping, uint dwDesiredAccess, uint dwFileOffsetHigh, uint dwFileOffsetLow, uint dwNumberOfBytesToMap);
    [DllImport("Kernel32.dll", CharSet = CharSet.Auto)]
    public static extern bool UnmapViewOfFile(IntPtr pvBaseAddress);
    [DllImport("Kernel32.dll", CharSet = CharSet.Auto)]
    public static extern bool CloseHandle(IntPtr handle);
    [DllImport("kernel32", EntryPoint = "GetLastError")]
    public static extern int GetLastError();
    const int ERROR_ALREADY_EXISTS = 183;
    const int FILE_MAP_COPY = 0x0001;
    const int FILE_MAP_WRITE = 0x0002;
    const int FILE_MAP_READ = 0x0004;
    const int FILE_MAP_ALL_ACCESS = 0x0002 | 0x0004;
    const int PAGE_READONLY = 0x02;
    const int PAGE_READWRITE = 0x04;
    const int PAGE_WRITECOPY = 0x08;
    const int PAGE_EXECUTE = 0x10;
    const int PAGE_EXECUTE_READ = 0x20;
    const int PAGE_EXECUTE_READWRITE = 0x40;
    const int SEC_COMMIT = 0x8000000;
    const int SEC_IMAGE = 0x1000000;
    const int SEC_NOCACHE = 0x10000000;
    const int SEC_RESERVE = 0x4000000;
    const int INVALID_HANDLE_VALUE = -1;
    IntPtr m_hSharedMemoryFile = IntPtr.Zero;
    IntPtr m_pwData = IntPtr.Zero;
    bool m_bAlreadyExist = false;
    bool m_bInit = false;
    long m_MemSize = 0;
    public ShareMem()
    {
    }
    ~ShareMem()
    {
        Close();
    }
    /// <summary>
    /// 初始化共享内存
    /// </summary>
    /// <param name="strName">共享内存名称</param>
    /// <param name="lngSize">共享内存大小</param>
    /// <returns></returns>
    public int Init(string strName, long lngSize)
    {
        if (lngSize <= 0 || lngSize > 104857600) lngSize = 104857600;
        //0x00800000
        m_MemSize = lngSize;
        if (strName.Length > 0)
        {
            //创建内存共享体(INVALID_HANDLE_VALUE)
            m_hSharedMemoryFile = CreateFileMapping(INVALID_HANDLE_VALUE, IntPtr.Zero, (uint)PAGE_READWRITE, 0, (uint)lngSize, strName);
            if (m_hSharedMemoryFile == IntPtr.Zero)
            {
                m_bAlreadyExist = false;
                m_bInit = false;
                return 2;
                //创建共享体失败
            }
            else
            {
                if (GetLastError() == ERROR_ALREADY_EXISTS)  //已经创建 
                {
                    m_bAlreadyExist = true;
                }
                else                                         //新创建 
                {
                    m_bAlreadyExist = false;
                }
            }
            //---------------------------------------
            //创建内存映射
            m_pwData = MapViewOfFile(m_hSharedMemoryFile, FILE_MAP_WRITE, 0, 0, (uint)lngSize);
            if (m_pwData == IntPtr.Zero)
            {
                m_bInit = false;
                CloseHandle(m_hSharedMemoryFile);
                return 3;
                //创建内存映射失败
            }
            else
            {
                m_bInit = true;
                if (m_bAlreadyExist == false)
                {
                    //初始化
                }
            }
            //----------------------------------------
        }
        else
        {
            return 1;
            //参数错误
        }
        return 0;
        //创建成功
    }
    /// <summary>
    /// 关闭共享内存
    /// </summary>
    public void Close()
    {
        if (m_bInit)
        {
            UnmapViewOfFile(m_pwData);
            CloseHandle(m_hSharedMemoryFile);
        }
    }
    /// <summary>
    /// 读数据
    /// </summary>
    /// <param name="bytData">数据</param>
    /// <param name="lngAddr">起始地址</param>
    /// <param name="lngSize">个数</param>
    /// <returns></returns>
    private int Read(ref byte[] bytData, int lngAddr, int lngSize)
    {
        if (lngAddr + lngSize > m_MemSize) return 2;
        //超出数据区
        if (m_bInit)
        {
            Marshal.Copy(m_pwData, bytData, lngAddr, lngSize);
        }
        else
        {
            return 1;
            //共享内存未初始化
        }
        return 0;
        //读成功
    }
    /// <summary>
    /// 写数据
    /// </summary>
    /// <param name="bytData">数据</param>
    /// <param name="lngAddr">起始地址</param>
    /// <param name="lngSize">个数</param>
    /// <returns></returns>
    private int Write(byte[] bytData, int lngAddr, int lngSize)
    {
        if (lngAddr + lngSize > m_MemSize) return 2;
        //超出数据区
        if (m_bInit)
        {
            Marshal.Copy(bytData, lngAddr, m_pwData, lngSize);
        }
        else
        {
            return 1;
            //共享内存未初始化
        }
        return 0;
        //写成功
    }

    public string Read()
    {
        byte[] byteStr = new byte[1024];

        int i = Read(ref byteStr, 0, byteStr.Length);
        string str = Encoding.Default.GetString(byteStr, 0, byteStr.Length);
        if (i == 0)
            return str.Replace("\0", "");
        else return "";

    }

    public int Write_Str(string byteStr)
    {

        if (byteStr == "")
        {
            byte[] sendStr = new byte[1024];
            return Write(sendStr, 0, sendStr.Length);
        }
        else
        {
            byte[] sendStr = Encoding.Default.GetBytes(byteStr + '\0');
            return Write(sendStr, 0, sendStr.Length);
        }

    }

}